Fluidization limit and slip structure in aqueous concentrated slurry containing hydrophobic hetero-particles in the presence of polymer-dispersant

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The SiC powders were pre-heated to evaluate the effect of the amount of free carbon and oxygen content on the surface of the SiC particles on the fluidity of the SiC slurries and the sintered density. Heating of the SiC powders at over 300℃ enhances the fluidity of the SiC slurries. The fluidity of C slurries was effectively enhanced by the addition of ammonium 2-naphthalene sulfonate formaldehyde condensate ( DEMOL-AS ) solution, compared with the addition of styrene/maleic copolymer ( SM ) solution with tetramethyl ammonium hydroxide ( TMAOH ) at pH 10-1 1. The SiC slurries with C and B_4C as sintering aids were prepared by controlling a pH of 10-11 with TMAOH and adding the optimum amount ofDEMOL-AS or SM to C content and then slip casting was conducted. The sintered body containing the SiC powders pre-heated at any temperatures was achieved the higher density of about 98 % Th. D. The SiC body of higher sintered density was possible to fabricate by controlling the addition of carbon, taking into account oxygen content on the surface of the SiC particles and the amount of free carbon.Zirconium acetate effectively enhanced the dispersion and fluidity of SiC slurries in the weakly acidic pH range. The optimum pH valuetod concentration of Zr-A for the SiC slurries were pH 3.5 and 0.5-1 wt % of the SiC, respectively. In aqueous media, Zr-A became a positively charged species. The SiC particles also exhibited a positively charged state at pH 3.5. Thus, the role of Zr-A in the dispersion of slurries should be interpreted as that of a depletion-stabilization mechanism.